> On 2. Mar 2026, at 17:16, Takashi YAMAMOTO <[email protected]> wrote: > > hi, > > On Mon, Mar 2, 2026 at 8:19 PM J. Hannken-Illjes <[email protected]> wrote: >> >>> On 1. Mar 2026, at 15:13, Takashi YAMAMOTO <[email protected]> wrote: >>> >>> On Fri, Feb 20, 2026 at 5:09 PM Takashi YAMAMOTO <[email protected]> wrote: >>>> >>>> hi, >>>> >>>> recently i have used netbsd zfs and have a few questions. >>>> >>>> * what's the purpose of zfs_zget_cleaner/VN_RELE_CLEANER? >>>> i have read the explanation in >>>> https://gnats.netbsd.org/cgi-bin/query-pr-single.pl?number=59885 . >>>> but i don't understand why we want to avoid the normal zfs_zget in >>>> the first place. >>>> for me, it seems working w/o these special versions of functions: >>>> https://github.com/yamt/netbsd-src/commit/438ec29437465e0b7e2b831d4452159f83cad0cf >>>> (i will attach the same patch to this mail for those who don't like >>>> github.) >>> >>> this version had a few deadlock issues. >>> >>> i will attach a fixed version i'm currently testing. >>> >>>> >>>> * is anyone using zfs in netbsd seriously? :-) >>>> >>>> * does anyone have a plan to update the codebase to recent openzfs? >>> <a.diff> >> >> This patch makes the situation better but it fires assertions during unmount. >> >> Running some stress tests on a 16-core amd64 vm with DEBUG+LOCKDEBUG and >> kern.maxvnodes=1105 unmount crashes as it tries to load a vnode during >> unmount: >> >> >> panic: kernel diagnostic assertion "mp == NULL || (mp->mnt_iflag & >> IMNT_UNMOUNT) == 0 || vp->v_tag == VT_VFS" failed: file >> "src/sys/kern/vfs_mount.c", line 545 >> >> #12 vfs_insmntque (vp=0xffffb751d4324a80, mp=0xffffb751cf2e2000) at >> src/sys/kern/vfs_mount.c:545 >> #13 vcache_get (mp=0xffffb751cf2e2000, key=key@entry=0xffffc3070a334bc8, >> key_len=key_len@entry=8, vpp=vpp@entry=0xffffc3070a334bd8) at >> src/sys/kern/vfs_vnode.c:1666 >> #14 zfs_zget (zfsvfs=zfsvfs@entry=0xffffc3002f7ba000, obj_num=<optimized >> out>, obj_num@entry=24865, zpp=zpp@entry=0xffffc3070a334c20) at >> src/sys/../external/cddl/osnet/dist/uts/common/fs/zfs/zfs_znode.c:1287 >> #15 zfs_get_data (arg=0xffffc3002f7ba000, lr=0xffffc30048cd41d8, >> buf=0xffffc30048cd4298 "", zio=0xffffb751e587e840) at >> src/sys/../external/cddl/osnet/dist/uts/common/fs/zfs/zfs_vnops.c:1500 >> #16 zil_lwb_commit (zilog=<optimized out>, itx=0xffffb7517fb6f5c0, >> lwb=0xffffb751bffa25f8) at >> src/sys/../external/cddl/osnet/dist/uts/common/fs/zfs/zil.c:1144 >> #17 zil_commit_writer (zilog=0xffffb751e664d540) at >> src/sys/../external/cddl/osnet/dist/uts/common/fs/zfs/zil.c:1556 >> #18 zil_commit (zilog=0xffffb751e664d540, foid=<optimized out>) at >> src/sys/../external/cddl/osnet/dist/uts/common/fs/zfs/zil.c:1638 >> #19 zil_commit (zilog=0xffffb751e664d540, foid=0) at >> src/sys/../external/cddl/osnet/dist/uts/common/fs/zfs/zil.c:1620 >> #20 zil_close (zilog=0xffffb751e664d540) at >> src/sys/../external/cddl/osnet/dist/uts/common/fs/zfs/zil.c:1856 >> #21 zfsvfs_teardown (zfsvfs=zfsvfs@entry=0xffffc3002f7ba000, >> unmounting=unmounting@entry=1) at >> src/sys/../external/cddl/osnet/dist/uts/common/fs/zfs/zfs_vfsops.c:2288 >> #22 zfs_umount (vfsp=0xffffb751cf2e2000, fflag=524288) at >> src/sys/../external/cddl/osnet/dist/uts/common/fs/zfs/zfs_vfsops.c:2445 >> #23 VFS_UNMOUNT (mp=mp@entry=0xffffb751cf2e2000, a=a@entry=524288) at >> src/sys/kern/vfs_subr.c:1526 >> #24 dounmount (mp=mp@entry=0xffffb751cf2e2000, flags=524288, >> l=l@entry=0xffffb751e855d800) at src/sys/kern/vfs_mount.c:980 >> #25 sys_unmount (l=0xffffb751e855d800, uap=0xffffc3070a335000, >> retval=<optimized out>) at src/sys/kern/vfs_syscalls.c:728 >> #26 sy_call (sy=0xffffffff8210a050 <sysent+528>, l=0xffffb751e855d800, >> uap=0xffffc3070a335000, rval=0xffffc3070a334fb0) at >> src/sys/sys/syscallvar.h:65 >> #27 sy_invoke (sy=0xffffffff8210a050 <sysent+528>, l=0xffffb751e855d800, >> uap=0xffffc3070a335000, rval=0xffffc3070a334fb0, code=22) at >> src/sys/sys/syscallvar.h:94 >> #28 syscall (frame=0xffffc3070a335000) at src/sys/arch/x86/x86/syscall.c:137 >> #29 handle_syscall () >> >> Here we have mp != NULL and mp->mnt_iflag == 0x122 (IMNT_MPSAFE | >> IMNT_NCLOOKUP | IMNT_UNMOUNT) > > it's an interesting crash. thank you. > i tried to reproduce it by myself. but no luck. > the attached patch (b.diff) would fix it.
Running vflush() until all vnodes are flushed works. I used the attached and
functinal equivalent diff and
my load tests ran for 6 hours without problem.
Allowing to attach new vnodes until the mount is IMNT_GONE looks ok.
Not sure we need to assert TAILQ_EMPTY(&mp->mnt_vnodelist), the "dangling
vnode" panic below should catch it.
> well, honestly speaking, i don't understand why zil_close commits the
> zil in the first place.
> my impression is that it should not be necessary because we are
> syncing txg for unmount anyway.
> what do you think?
No idea -- its been much too long I looked deeper int ZFS internals.
>> Disabling this assertion zfs unmount fails to destroy a list as it is not
>> empty:
>>
>>
>> panic: solaris assert: list->list_head.list_next == node, file:
>> src/sys/../external/cddl/osnet/dist/uts/common/os/list.c, line: 86
>>
>> #12 list_destroy (list=list@entry=0xffff940059153040) at
>> src/sys/../external/cddl/osnet/dist/uts/common/os/list.c:86
>> #13 zfsvfs_free (zfsvfs=0xffff940059152000) at
>> src/sys/../external/cddl/osnet/dist/uts/common/fs/zfs/zfs_vfsops.c:1439
>> #14 zfs_freevfs (vfsp=0xffff859a2e81d000) at
>> src/sys/../external/cddl/osnet/dist/uts/common/fs/zfs/zfs_vfsops.c:2782
>> #15 zfs_umount (vfsp=0xffff859a2e81d000, fflag=<optimized out>) at
>> src/sys/../external/cddl/osnet/dist/uts/common/fs/zfs/zfs_vfsops.c:2471
>> #16 VFS_UNMOUNT (mp=mp@entry=0xffff859a2e81d000, a=a@entry=524288) at
>> src/sys/kern/vfs_subr.c:1526
>> #17 dounmount (mp=mp@entry=0xffff859a2e81d000, flags=524288,
>> l=l@entry=0xffff859a6a698400) at src/sys/kern/vfs_mount.c:980
>> #18 sys_unmount (l=0xffff859a6a698400, uap=0xffff94070afdc000,
>> retval=<optimized out>) at src/sys/kern/vfs_syscalls.c:728
>> #19 sy_call (sy=0xffffffff8210a050 <sysent+528>, l=0xffff859a6a698400,
>> uap=0xffff94070afdc000, rval=0xffff94070afdbfb0) at
>> src/sys/sys/syscallvar.h:65
>> #20 sy_invoke (sy=0xffffffff8210a050 <sysent+528>, l=0xffff859a6a698400,
>> uap=0xffff94070afdc000, rval=0xffff94070afdbfb0, code=22) at
>> src/sys/sys/syscallvar.h:94
>> #21 syscall (frame=0xffff94070afdc000) at src/sys/arch/x86/x86/syscall.c:137
>> #22 handle_syscall ()
>>
>> where *list is (list_t *) 0xffff940059153040:
>>
>> {
>> list_size = 240,
>> list_offset = 200,
>> list_head = {
>> list_next = 0xffff859a07007ab8,
>> list_prev = 0xffff8599c322bea8
>> }
>> }
>>
>> --
>> J. Hannken-Illjes - [email protected]
> <b.diff>
--
J. Hannken-Illjes - [email protected]
b1.diff
Description: Binary data
